"""
Support for BME680 Sensor over SMBus.

Temperature, humidity, pressure and volatile gas support.
Air Quality calculation based on humidity and volatile gas.

For more details about this platform, please refer to the documentation at
https://home-assistant.io/components/sensor.bme680/
"""
import asyncio
import logging

from time import time, sleep

import voluptuous as vol

from homeassistant.components.sensor import PLATFORM_SCHEMA
import homeassistant.helpers.config_validation as cv
from homeassistant.const import (
    TEMP_FAHRENHEIT, CONF_NAME, CONF_MONITORED_CONDITIONS)
from homeassistant.helpers.entity import Entity
from homeassistant.util.temperature import celsius_to_fahrenheit

REQUIREMENTS = ['bme680==1.0.4',
                'smbus-cffi==0.5.1']

_LOGGER = logging.getLogger(__name__)

CONF_I2C_ADDRESS = 'i2c_address'
CONF_I2C_BUS = 'i2c_bus'
CONF_OVERSAMPLING_TEMP = 'oversampling_temperature'
CONF_OVERSAMPLING_PRES = 'oversampling_pressure'
CONF_OVERSAMPLING_HUM = 'oversampling_humidity'
CONF_FILTER_SIZE = 'filter_size'
CONF_GAS_HEATER_TEMP = 'gas_heater_temperature'
CONF_GAS_HEATER_DURATION = 'gas_heater_duration'
CONF_AQ_BURN_IN_TIME = 'aq_burn_in_time'
CONF_AQ_HUM_BASELINE = 'aq_humidity_baseline'
CONF_AQ_HUM_WEIGHTING = 'aq_humidity_bias'


DEFAULT_NAME = 'BME680 Sensor'
DEFAULT_I2C_ADDRESS = 0x77
DEFAULT_I2C_BUS = 1
DEFAULT_OVERSAMPLING_TEMP = 8  # Temperature oversampling x 8
DEFAULT_OVERSAMPLING_PRES = 4  # Pressure oversampling x 4
DEFAULT_OVERSAMPLING_HUM = 2  # Humidity oversampling x 2
DEFAULT_FILTER_SIZE = 3  # IIR Filter Size
DEFAULT_GAS_HEATER_TEMP = 320  # Temperature in celsius 200 - 400
DEFAULT_GAS_HEATER_DURATION = 150  # Heater duration in ms 1 - 4032
DEFAULT_AQ_BURN_IN_TIME = 300  # 300 second burn in time for AQ gas measurement
DEFAULT_AQ_HUM_BASELINE = 40  # 40%, an optimal indoor humidity.
DEFAULT_AQ_HUM_WEIGHTING = 25  # 25% Weighting of humidity to gas in AQ score

SENSOR_TEMP = 'temperature'
SENSOR_HUMID = 'humidity'
SENSOR_PRESS = 'pressure'
SENSOR_GAS = 'gas'
SENSOR_AQ = 'airquality'
SENSOR_TYPES = {
    SENSOR_TEMP: ['Temperature', None],
    SENSOR_HUMID: ['Humidity', '%'],
    SENSOR_PRESS: ['Pressure', 'mb'],
    SENSOR_GAS: ['Gas Resistance', 'Ohms'],
    SENSOR_AQ: ['Air Quality', '%']
}
DEFAULT_MONITORED = [SENSOR_TEMP, SENSOR_HUMID, SENSOR_PRESS, SENSOR_AQ]
OVERSAMPLING_VALUES = set([0, 1, 2, 4, 8, 16])
FILTER_VALUES = set([0, 1, 3, 7, 15, 31, 63, 127])

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
    vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
    vol.Optional(CONF_I2C_ADDRESS, default=DEFAULT_I2C_ADDRESS):
        cv.positive_int,
    vol.Optional(CONF_MONITORED_CONDITIONS, default=DEFAULT_MONITORED):
        vol.All(cv.ensure_list, [vol.In(SENSOR_TYPES)]),
    vol.Optional(CONF_I2C_BUS, default=DEFAULT_I2C_BUS): cv.positive_int,
    vol.Optional(CONF_OVERSAMPLING_TEMP, default=DEFAULT_OVERSAMPLING_TEMP):
        vol.All(vol.Coerce(int), vol.In(OVERSAMPLING_VALUES)),
    vol.Optional(CONF_OVERSAMPLING_PRES, default=DEFAULT_OVERSAMPLING_PRES):
        vol.All(vol.Coerce(int), vol.In(OVERSAMPLING_VALUES)),
    vol.Optional(CONF_OVERSAMPLING_HUM, default=DEFAULT_OVERSAMPLING_HUM):
        vol.All(vol.Coerce(int), vol.In(OVERSAMPLING_VALUES)),
    vol.Optional(CONF_FILTER_SIZE, default=DEFAULT_FILTER_SIZE):
        vol.All(vol.Coerce(int), vol.In(FILTER_VALUES)),
    vol.Optional(CONF_GAS_HEATER_TEMP, default=DEFAULT_GAS_HEATER_TEMP):
        vol.All(vol.Coerce(int), vol.Range(200, 400)),
    vol.Optional(CONF_GAS_HEATER_DURATION,
                 default=DEFAULT_GAS_HEATER_DURATION):
        vol.All(vol.Coerce(int), vol.Range(1, 4032)),
    vol.Optional(CONF_AQ_BURN_IN_TIME, default=DEFAULT_AQ_BURN_IN_TIME):
        cv.positive_int,
    vol.Optional(CONF_AQ_HUM_BASELINE, default=DEFAULT_AQ_HUM_BASELINE):
        vol.All(vol.Coerce(int), vol.Range(1, 100)),
    vol.Optional(CONF_AQ_HUM_WEIGHTING, default=DEFAULT_AQ_HUM_WEIGHTING):
        vol.All(vol.Coerce(int), vol.Range(1, 100)),
})


@asyncio.coroutine
def async_setup_platform(hass, config, async_add_entities,
                         discovery_info=None):
    """Set up the BME680 sensor."""
    SENSOR_TYPES[SENSOR_TEMP][1] = hass.config.units.temperature_unit
    name = config.get(CONF_NAME)

    sensor_handler = yield from hass.async_add_job(_setup_bme680, config)
    if sensor_handler is None:
        return

    dev = []
    for variable in config[CONF_MONITORED_CONDITIONS]:
        dev.append(BME680Sensor(
            sensor_handler, variable, SENSOR_TYPES[variable][1], name))

    async_add_entities(dev)
    return


# pylint: disable=import-error, no-member
def _setup_bme680(config):
    """Set up and configure the BME680 sensor."""
    from smbus import SMBus
    import bme680

    sensor_handler = None
    sensor = None
    try:
        i2c_address = config.get(CONF_I2C_ADDRESS)
        bus = SMBus(config.get(CONF_I2C_BUS))
        sensor = bme680.BME680(i2c_address, bus)

        # Configure Oversampling
        os_lookup = {
            0: bme680.OS_NONE,
            1: bme680.OS_1X,
            2: bme680.OS_2X,
            4: bme680.OS_4X,
            8: bme680.OS_8X,
            16: bme680.OS_16X
        }
        sensor.set_temperature_oversample(
            os_lookup[config.get(CONF_OVERSAMPLING_TEMP)]
        )
        sensor.set_humidity_oversample(
            os_lookup[config.get(CONF_OVERSAMPLING_HUM)]
        )
        sensor.set_pressure_oversample(
            os_lookup[config.get(CONF_OVERSAMPLING_PRES)]
        )

        # Configure IIR Filter
        filter_lookup = {
            0: bme680.FILTER_SIZE_0,
            1: bme680.FILTER_SIZE_1,
            3: bme680.FILTER_SIZE_3,
            7: bme680.FILTER_SIZE_7,
            15: bme680.FILTER_SIZE_15,
            31: bme680.FILTER_SIZE_31,
            63: bme680.FILTER_SIZE_63,
            127: bme680.FILTER_SIZE_127
        }
        sensor.set_filter(
            filter_lookup[config.get(CONF_FILTER_SIZE)]
        )

        # Configure the Gas Heater
        if (
                SENSOR_GAS in config[CONF_MONITORED_CONDITIONS] or
                SENSOR_AQ in config[CONF_MONITORED_CONDITIONS]
        ):
            sensor.set_gas_status(bme680.ENABLE_GAS_MEAS)
            sensor.set_gas_heater_duration(config[CONF_GAS_HEATER_DURATION])
            sensor.set_gas_heater_temperature(config[CONF_GAS_HEATER_TEMP])
            sensor.select_gas_heater_profile(0)
        else:
            sensor.set_gas_status(bme680.DISABLE_GAS_MEAS)
    except (RuntimeError, IOError):
        _LOGGER.error("BME680 sensor not detected at 0x%02x", i2c_address)
        return None

    sensor_handler = BME680Handler(
        sensor,
        True if (
            SENSOR_GAS in config[CONF_MONITORED_CONDITIONS] or
            SENSOR_AQ in config[CONF_MONITORED_CONDITIONS]
        ) else False,
        config[CONF_AQ_BURN_IN_TIME],
        config[CONF_AQ_HUM_BASELINE],
        config[CONF_AQ_HUM_WEIGHTING]
    )
    sleep(0.5)  # Wait for device to stabilize
    if not sensor_handler.sensor_data.temperature:
        _LOGGER.error("BME680 sensor failed to Initialize")
        return None

    return sensor_handler


class BME680Handler:
    """BME680 sensor working in i2C bus."""

    class SensorData:
        """Sensor data representation."""

        def __init__(self):
            """Initialize the sensor data object."""
            self.temperature = None
            self.humidity = None
            self.pressure = None
            self.gas_resistance = None
            self.air_quality = None

    def __init__(
            self, sensor, gas_measurement=False,
            burn_in_time=300, hum_baseline=40, hum_weighting=25
    ):
        """Initialize the sensor handler."""
        self.sensor_data = BME680Handler.SensorData()
        self._sensor = sensor
        self._gas_sensor_running = False
        self._hum_baseline = hum_baseline
        self._hum_weighting = hum_weighting
        self._gas_baseline = None

        if gas_measurement:
            import threading
            threading.Thread(
                target=self._run_gas_sensor,
                kwargs={'burn_in_time': burn_in_time},
                name='BME680Handler_run_gas_sensor'
            ).start()
        self.update(first_read=True)

    def _run_gas_sensor(self, burn_in_time):
        """Calibrate the Air Quality Gas Baseline."""
        if self._gas_sensor_running:
            return

        self._gas_sensor_running = True

        # Pause to allow initial data read for device validation.
        sleep(1)

        start_time = time()
        curr_time = time()
        burn_in_data = []

        _LOGGER.info("Beginning %d second gas sensor burn in for Air Quality",
                     burn_in_time)
        while curr_time - start_time < burn_in_time:
            curr_time = time()
            if (
                    self._sensor.get_sensor_data() and
                    self._sensor.data.heat_stable
            ):
                gas_resistance = self._sensor.data.gas_resistance
                burn_in_data.append(gas_resistance)
                self.sensor_data.gas_resistance = gas_resistance
                _LOGGER.debug("AQ Gas Resistance Baseline reading %2f Ohms",
                              gas_resistance)
                sleep(1)

        _LOGGER.debug("AQ Gas Resistance Burn In Data (Size: %d): \n\t%s",
                      len(burn_in_data), burn_in_data)
        self._gas_baseline = sum(burn_in_data[-50:]) / 50.0
        _LOGGER.info("Completed gas sensor burn in for Air Quality")
        _LOGGER.info("AQ Gas Resistance Baseline: %f", self._gas_baseline)
        while True:
            if (
                    self._sensor.get_sensor_data() and
                    self._sensor.data.heat_stable
            ):
                self.sensor_data.gas_resistance = (
                    self._sensor.data.gas_resistance
                )
                self.sensor_data.air_quality = self._calculate_aq_score()
                sleep(1)

    def update(self, first_read=False):
        """Read sensor data."""
        if first_read:
            # Attempt first read, it almost always fails first attempt
            self._sensor.get_sensor_data()
        if self._sensor.get_sensor_data():
            self.sensor_data.temperature = self._sensor.data.temperature
            self.sensor_data.humidity = self._sensor.data.humidity
            self.sensor_data.pressure = self._sensor.data.pressure

    def _calculate_aq_score(self):
        """Calculate the Air Quality Score."""
        hum_baseline = self._hum_baseline
        hum_weighting = self._hum_weighting
        gas_baseline = self._gas_baseline

        gas_resistance = self.sensor_data.gas_resistance
        gas_offset = gas_baseline - gas_resistance

        hum = self.sensor_data.humidity
        hum_offset = hum - hum_baseline

        # Calculate hum_score as the distance from the hum_baseline.
        if hum_offset > 0:
            hum_score = (
                (100 - hum_baseline - hum_offset) /
                (100 - hum_baseline) *
                hum_weighting
            )
        else:
            hum_score = (
                (hum_baseline + hum_offset) /
                hum_baseline *
                hum_weighting
            )

        # Calculate gas_score as the distance from the gas_baseline.
        if gas_offset > 0:
            gas_score = (gas_resistance / gas_baseline) * (100 - hum_weighting)
        else:
            gas_score = 100 - hum_weighting

        # Calculate air quality score.
        return hum_score + gas_score


class BME680Sensor(Entity):
    """Implementation of the BME680 sensor."""

    def __init__(self, bme680_client, sensor_type, temp_unit, name):
        """Initialize the sensor."""
        self.client_name = name
        self._name = SENSOR_TYPES[sensor_type][0]
        self.bme680_client = bme680_client
        self.temp_unit = temp_unit
        self.type = sensor_type
        self._state = None
        self._unit_of_measurement = SENSOR_TYPES[sensor_type][1]

    @property
    def name(self):
        """Return the name of the sensor."""
        return '{} {}'.format(self.client_name, self._name)

    @property
    def state(self):
        """Return the state of the sensor."""
        return self._state

    @property
    def unit_of_measurement(self):
        """Return the unit of measurement of the sensor."""
        return self._unit_of_measurement

    @asyncio.coroutine
    def async_update(self):
        """Get the latest data from the BME680 and update the states."""
        yield from self.hass.async_add_job(self.bme680_client.update)
        if self.type == SENSOR_TEMP:
            temperature = round(self.bme680_client.sensor_data.temperature, 1)
            if self.temp_unit == TEMP_FAHRENHEIT:
                temperature = round(celsius_to_fahrenheit(temperature), 1)
            self._state = temperature
        elif self.type == SENSOR_HUMID:
            self._state = round(self.bme680_client.sensor_data.humidity, 1)
        elif self.type == SENSOR_PRESS:
            self._state = round(self.bme680_client.sensor_data.pressure, 1)
        elif self.type == SENSOR_GAS:
            self._state = int(
                round(self.bme680_client.sensor_data.gas_resistance, 0)
            )
        elif self.type == SENSOR_AQ:
            aq_score = self.bme680_client.sensor_data.air_quality
            if aq_score is not None:
                self._state = round(aq_score, 1)
